Light-control switch



1,618,816 Feb. 22,1927. H DAVIES Q LIGHT CONTROL SWITCH Original FiledMay 5, 1918 amuenfo c Henry R fla /es Patented Feb. 22, 1927. I

NITED STATES I 1,618,816; PATENT ,OFFICE.

HENRY B. DAVIES, OI VALLEY COTTAGE, NEW YORK, ASSIGNOR TO INDUSTRIAL RE-SEARCH COBDOBATION, OF TOLEDO, 01110, A CORPORATION OF DELAWARE.

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Application filed Kay 8, 1918, Serial No. 282,244. Renewed April 16,1926.

This invention relates to control means for automatically cutting in andout, the current in lighting or power circuits dependent upon thepresence of light. I

The principal object of the invention is to provide means forautomatically operating the switch in the circuit of the translatingdevice. I

Another object is to utilize a switch which is responsive to theintensity of light instant upon the switch.

Further objects, andobjects relating to economics of manufacture anddetails of .construction, will definitely appear from the 16 detaileddescription to follow.

I accomplish the objects of my invention by the devices described in thefollowing specification. My invention is clearly defined and pointed outin the appended claims.

An arrangement constitutinga preferred embodiment of my invention isillustrated in the accompanying drawing. forming a part of thisspecification, in which:

' Fig. I is a diagrammatic view illustrat- 25 ing the various parts ofthe system, and

the connections thereto, as applied to a charging and lighting systemfor automobiles, and

Fi II is a detail view, showing the switc in open position.

In the drawings, similar reference numerals refer to similar partsthroughout the several views.

As illustrated, I have shown a dynamo 35 electric machine 1 having mainbrushes 2 and 3, to which are connected the power mains 4 and 5. Therelay or cut-out 6 is of a form commonly employed in lighting systemsfor automobiles, and consists in a shunt coil 7 and a series coil 8,which are adapted to energize a core 9 at a predetermined voltage.thereby closing the contacts 10 and 11 of the power main 5. Connectedacross the mains 4 and 5 is the storage battery 12, which is utilizedfor the purpose of supplying power when the generator is inactive.Translating devices 13 are also indicated in the form of lamps.

The generator 1 and the battery 12 are in parallel, so that either maysupply current to the lamps 13 over the power mains. Interposed in themain 5 is a switch 14, which has contacts 15 and 16 and an operating arm17. In the form shown, this arm 17 is made of two metallic strips havingdifferent thermal co-efiicients of expansion, and these strips are sopositioned relative to each other, that when subjected to the sameheating influence, the greater expansion of the one over that of theother will cause a warping of the arm 17, thereby opening thecontacts 15and 16.

For heating the arm 17, and thereby op erating the switch, I utilize aheating coil 18 which is connected across the mains in parallel with thestorage battery. In series with this heating coil, I employ a resistanceelement 19, and a light sensitive element 20. In the form, as at presentemployed, this light sensitive element consists in a strip of seleniummetal which has the well known property of decreasing its resistance tothe passage of electric current when subjected to the influence oflight.

In order to prevent heating of the warping elements of the arm 17, thepowermain is shunted around-this arm as indicated by the connection 21,the terminal of the connection being attached to the contact 16 of theswitch. I also employ a second circuit 22 in parallel with the automaticswitch 14, in which is a manual switch 23 which may be employed to cutout the automatic switch. A manually operated switch 25 is provided sothat the circuit through the translating devices 13 may be opened ifdesired while the automatic switch 14'is closed.

In the practical utilization. of my invention, as applied toautomobiles, the light sensitive element 20 is so positioned as to besubject to changes in the intensity of sun light. When there is anabsence of all light, the switch 14 assumes its normal position asindicated in Fig. I, with the contacts 15 and 16 in closed position.With this switch closed, the current from the storage battery or fromthe generator has a free passage to the electric elements 13, which areaccordingly illuminated- Some current, of course, passes through theheating coil 18, but inasmuch as the resistance ofthe'light sensitiveelement 20 is very high the heating efi'ect of the coil 18 is so smallthatoperation of the automatic switch is prevented. However, as soon asthe light waves impinge upon the light sensitive element 20, theresistance thereof is materially decreased with a resultant increase ofthe current passing through the heating coil. This causes an unequalexpansion of the metal arms of the strips 17, which causes the contacts15 and 110 "16 to open, as illustrated in Figure II, there-' by openingthe electric circuit through the lamps 13. 7

From the above description, it is evident that I have provided means forautomatically turning on the lights when the daylight en diminishes, andturning oil the lights w the daylight increases. This arrangement 1sparticularly desirable where cars are left on city streetswhere civicregulations require that tail lights and headlights be burning aftercertain hours.

I am aware that the particular embodiment of my invention is susceptibleof considerable variation without departing from the spirit of myinvention, and, therefore, I desire to claim the same broadly, as well'as specifically, as indicated by the appended claims.

Having thus described my invention, what I claim as new and-desire tosecure by Letters Patent, is: 1.- In combination, a source ofelectricity;

' translating devices; connections between the electrical translatdevices, conductors intermediate the tra ating devices and sourceofelectricit a switch in series with said eonductors; t ermosensitiveoperating means for said switch; a heating'coil on said thermosens-itiveoperating means connected in parallel with the translating devices; anda 1ght sensltive unit in series with said heatmg coil, adapted to varythe current in the heating coil with the intensity of illumination onthe light sensitive unit; and a current carrying shunt around thethermosensitive ortion of said switch.

3. combination, a source of electricit translating devices; a circuitbetween t e electrical source and translating devices; a switch inseries with said circuit; thermosensitive operating means for saidswitch; a heating coil in operative relationship with saidthermo-sensitive operating. means; and a light sensitive unitoperatively connected with said heating coil adapted to increase thecurrent therein when the light sensitive unit is subjected to theinfluence of light- 4. In combination, a source of electricity;translating devices connected to said source; circuit connectionsbetween the electrical source and the translating devices;thermosensitive means adapted to open said circuit; and a lightsensitive unit in operative relationship with said thermosensitive meansadapted to bring about energization of said means to 'open the circuit.

In testimony whereof, I affix-my signature.

HENRY R. DAVIES.

